Automatic Duration calculation from 2 Predecessory



I have a Task B that cannot start before Task A was finished and that should finish the same time as Task C.

When I enter 2 predecessors for B, namely that Task A has FS and Task C has FF, the smartsheet always takes into account only one of the Predecessors and puts the duration on 1d automatically (see screenshots).

However, I want the duration to be flexible but I want the 2 predecessor conditions to be fixed! So when I would change the start date of Task A, the duration should change automatically acccording to the 2 predecessors conditions.

How can I do that??

Thank you very much!

Best regards